aioble/multitests: Adjust expected output for write capture test.

Testing shows that the first two writes always go through and the rest are
dropped, so update the .exp file to match that.

Signed-off-by: Damien George <damien@micropython.org>

micropython/bluetooth/aioble/multitests/ble_write_capture.py.exp

@@ -2,7 +2,7 @@
 advertise
 connected
 written b'central0'
-written b'central2'
+written b'central1'
 written b'central0' True
 written b'central1' True
 written b'central2' True